The present invention relates to a tape cassette for use in a magnetic recording and reproducing device such as a video tape recorder (VTR) and more particularly to a tape cassette for use as a video tape cassette such as an 8 mm video tape cassette and a digital video cassette (DVC) which has a tape-like medium received in a case thereof via tape reels and incorporates therein a reel brake mechanism for regulating the rotation of the tape reels when the tape cassette is not in use.
Conventionally, in a tape cassette in which a pair of tape reels around which a tape-like medium is wound are rotatably installed in a case thereof, a brake mechanism for stopping the rotation of the tape reels when the tape cassette is not in use is widely used which is constructed such that a brake member is biased against teeth provided on outer circumferences of flanges of the tape reels by means of a resilient member such as a torsional coil spring and a leaf spring, and when this tape cassette so constructed is mounted in the recording and reproducing device, a brake releasing member of the recording and reproducing device is brought into abutment with the brake member and moves the brake member against the resilient force of the spring so as to disengage the brake member from the tape reels to thereby allow the tape reels to rotate (Japanese Unexamined Patent Publication Nos. 6-318383 and 10-112158, and Japanese Unexamined Utility Model Publication Nos. 3-106587 and 58-173073).
FIGS. 31A and 31B are plan views showing one example of a conventional reel brake for a tape cassette, FIG. 31A showing a state in which the reel brake is in normal use, and FIG. 31B showing a state in which pawls are deployed. Arms 826 are provided on left and right sides of a main body 821 of the reel brake 820 in such a manner as to outwardly protrude therefrom. This arm 826 and the pawl 822 are connected to each other at a thin hinge portion 824. The pawl 822 comprises a distal end portion 822a, a guided portion 822b and a root portion 822c which are integrally formed. The pawl 822 is formed so as to rotate about the hinge portion 824 as a fulcrum, and they are so constructed as to allow the pawl 822 to rotate appropriately when the distal end portion 822a of the pawl 822 is brought into engagement with teeth formed in a tape reel to thereby provide a smooth engagement between the pawl 822 and the teeth.
The reel brake 820 is disposed in the tape cassette in a state as shown in FIG. 31A, in which the guided portion 822b engages a guide groove formed on a case main body side.
In the aforesaid conventional reel brake for a tape cassette, however, a number of reel brakes are received as one of parts for a tape cassette in a box or the like for transportation after they are formed until they are incorporated into a tape cassette, and in assembling, they are put in volume in a part feeder or the like of an automatic assembling machine. During these stages, reel brakes 820 get entangled in each other, and as shown in FIG. 31B, the pawl 822 is unnecessarily rotated (excessive rotation), and moreover this repeatedly happens, since the thickness of the hinge portion 824 is extremely thin (e.g., on the order of 0.13 mm), there is caused a cut (crack) in the hinge portion 824 and there may be even a case where the hinge portion 824 is cut thereat.
In addition, when the reel brake 820 is used in a state in which there is cause to cut in the hinge portion 824, the hinge portion 824 is cut while in use, thereby causing a problem that the reel brake 820 cannot fulfill the function to lock the tape reels.
Furthermore, although the strength of the hinge portion 824 is improved if a resin material (for instance, polypropylene) is used which has a hinge effect strong enough to deal with repeated bending, since materials have to be selected while taking into consideration the moldability and slidability of the reel brake 820, there has been a certain limit to increasing the strength of the hinge portion 824.
FIGS. 32A and 32B shows an example of another conventional reel brake, in which FIG. 32A is a plan view showing a state in which a reel brake 908 mounted in a lower case 902 engages teeth 903d formed in a tape reel 903 and FIG. 32B is a sectional view corresponding to a plane Axe2x80x94A of FIG. 32A and showing a state in which an upper case 901 is mounted on the lower case 902.
The teeth 903d are formed in an outer circumference of the tape reel 903. In addition, in FIG. 32A, the reel brake 908 is disposed slidably in vertical directions. Pawls 908c are provided on left and right sides of a main body 908a of the reel brake 908, which pawls 908c are adapted to freely rotate via thinned hinge portions 908b. 
The reel brake 908 is biased toward the tape reel 903 side by virtue of a spring force of a spring (not shown) when the tape cassette is not in use, and the tape reel 903 is locked when the pawl 908c of the reel brake 908 enters between the teeth 903d formed in the tape reel 903.
In addition, when the tape cassette is in use, the reel brake 908 is slid in a direction in which it moves away from the tape reel 903 against the biasing force of the spring, whereby the engagement between the reel brake 908 and the tape reel 903 is released.
Furthermore, a position regulating portion 902b, for regulating the position of the reel brake 908, is provided in the lower case 902 in such a manner as to be erect therefrom. A front of the main body 908a of the reel brake 908 and a position regulating wall 902b are constructed so as to be brought into abutment with each other at a position where a distal end of the pawl 908c of the reel brake 908 engages the teeth 903d of the reel brake 903, whereby the reel brake 908 is prevented from sliding further toward the tape reel 903 side from this regulated position.
In the conventional tape cassette, however, since a gate portion 908f exists in the front of the main body 908a of the reel brake 908, there is no problem caused when the gate portion 908f is flat, but as shown in FIGS. 32A and 32B, in a case where there remains a projection (the remains of the gate) at the gate portion 908f, there is caused a problem that the front of the main body 908a does not abut with the position regulating wall 902b, but only the gate portion 908a abuts therewith, and there may be caused a risk in which the reel brake 908 is not allowed to slide to an original engagement position where the reel brake 908 engages the teeth 903d of the tape reel 903.
Even if the distal end of the pawl 908c of the reel brake 908 engages the teeth 903d of the tape reel 903, the engagement therebetween becomes insufficient, and this causes a problem that the designed braking function cannot be securely performed.
Here, to deal with the aforesaid problem, first of all, it is considered to finish the gate after the reel brake 908 is formed such as by cutting a projection with a pair of nippers or grinding away the same with a file. However, a processing like this involves a problem of increased costs.
Secondly, it is considered to dispose the gate of the reel brake 908 at a position other than in the front of the main body 908a of the reel brake 908. However, upper and lower surfaces of the main body 908a of the reel brake 908 are brought into abutment with internal walls of the upper case 901 and the lower case 902 and constitute a sliding surface for the reel brake 908, and therefore if the gate portion 908f is provided in these surfaces, there may be caused a risk of a sliding failure, which is not preferable.
In addition, generally, the back of the main body 908a is a surface which is adapted to be brought into abutment with a spring for biasing the reel brake 908 and therefore, the configuration thereof becomes complicated, and it is not preferable to provide the gate portion 908f in this back. On the other hand, it is preferable to provide the gate portion 908f at a central portion of the front of the main body 908f of the reel brake 908 from the viewpoint of formability of the thinned hinge portion 908b for allowing the rotation of the pawl 908c. In other words, if the gate portion 908f is provided at a position offset either to the left-hand side or the right-hand side of the main body 908a, the formability of the thinned hinge portion 908b is deteriorated.
Thirdly, it is considered to lower the height of the position regulating wall 902b to a height where an abutment with the gate portion 908f can be avoided. However, in this case, there is caused a problem that the reel brake 908 is liable to fall forward when the reel brake 908 abuts with the position regulating wall 902b. 
However, in recent years, as various types of recording and reproducing devices have been developed and marketed, brake release devices equipped on such devices or device side brake release devices have also been diversified. In a cassette tape having a reel brake member that is maneuvered, for instance, with a pin, the size and depth of openings formed in a lower case or on a lower surface side of a reel brake member are standardized, but in brake release members provided on a device side, there are pins of various configurations, such as square pole-like or cylindrical, and the thickness thereof also ranges from thin to thick. Also, the configuration of the tips of the pins range from slanted to spherical tips, so that the thickness and configuration appears to vary from manufacturer to manufacturer.
Namely, there are a number of designs adopted for the position and tip configuration of pins and they vary from model to model or from manufacturer to manufacturer. When a reel brake member retires to a standardized brake release position, if the position of a brake release pin is offset, or a pin is inclined, it is highly probable that a brake pawl continues to stay in the reel areas, and if this happens, there is caused a problem that the tape reel cannot rotate in a normal fashion.
In particular, in the case of a video camera, in order to cope with the tendency in which cameras are made smaller in size and lighter in weight, the number of thin pin-like members is being increased. In operation and maneuvering of this type of release pin, if there is caused relative deviation in position between the pin and the reel brake opening of a cassette, or, for instance, such a deviation in position is caused by the tolerance or variation in production of a cassette or variation in production of a device, it may be not possible to press the central portion of the reel brake member. In that case, since a force is caused to act on the reel brake member in a direction in which the member rotates, a great magnitude of force is required to release the brake, and therefore a smooth braking operation cannot be effected or depending on a device, the device may be out of order, this causing a problem in handling of the device.
Consequently, an object of the present invention is to prevent the generation of a cut in a thin hinge portion via which a pawl of a reel brake for a tape cassette becomes rotatable due to excessive rotations of the pawl, for instance, while being transported.
Therefore, an object of the present invention is to prevent an interference between the gate portion of the reel brake and the position regulating portion of the case main body while maintaining the formability of the reel brake.
The present invention was made to easily eliminate the aforesaid problems inherent in the prior art, and an object thereof is to provide at reasonable costs a tape cassette that can press for actuation a central portion of a reel brake member even if there are various types of reel brake members resulting from a variety of types of devices used together for a smooth brake releasing operation, which can maintain the normal brake function so as to eliminate a problem in handling for a secure brake operation and which incorporates therein a functionally satisfactory brake mechanism.
The present invention was made to easily eliminate the aforesaid problems inherent in the prior art, and an object thereof is to provide a tape cassette wherein a reel brake mechanism for stopping the rotation of a pair of tape reels rotatably received inside a case of the tape cassette is constructed such that even if a strong impact such as a drop impact is exerted thereon, a brake engagement is not released to thereby prevent the production of a looseness of the tape so that the tape cassette can perfectly be used, wherein the reel brake mechanism is constructed such that a reel brake member is prevented from being moved even if the tape reels are moved inside the tape cassette to thereby eliminate unnecessary movements of the reel brake member so that the reel brake member can follow every movement of the tape reels, thereby making it possible to maintain a highly reliable reel brake performance, and wherein the number of components used is reduced to as few as possible so as to improve the assembling capability and increase the productivity, thereby making it possible to provide an inexpensive tape cassette incorporating therein a reel brake mechanism that can perform a positive brake operation and which satisfies functional requirements.
With a view to attaining the aforesaid object, according to the first aspect of the invention, a tape cassette comprises a reel brake for a tape cassette, a pair of tape reels around which a tape is wound being rotatably received in a case main body so as to prevent idle rotations of the tape reels through engagement with the tape reels when the tape cassette is not in use, wherein the reel brake comprises pawls provided on a main body thereof and each having a thinned hinge portion, the pawl being formed so as to rotate through the hinge portion and comprising a regulating portion for preventing excessive rotations of the pawl.
Preferably, the regulating portion comprises a regulating rib provided so as to extend from the vicinity of the hinge portion, and wherein an end of the regulating rib is adapted to abut with an end of an arm located on an opposite side and connected to the rib via the hinge portion when the pawl rotates excessively.
Moreover, the regulating portion comprises a regulating rib provided between a pair of the hinge portions of the main body.
In the first aspect of the present invention, the pawl can rotate via the hinge portion, but when the pawl is rotated excessively, the pawl and the main body of the reel brake are brought into abutment with the regulating portion. Consequently, a further rotation of the pawl can be prevented, whereby even when reel brakes get entangled in each other to thereby rotate the pawls excessively, since a rotation of the pawl exceeding a certain angle is regulated by the regulating portion, the generation of a cut in the hinge portion can be prevented.
With a view to attaining the aforesaid object, according to the second aspect of the invention, a tape cassette comprises: tape reels around which a tape-like medium is wound after being rotatably received in a case main body; a reel brake, for preventing idle rotations of the tape reels, through engagement with the tape reels, when the tape cassette is not in use, the reel brake being slidably disposed between a locked or brake position, wherein the tape reels are locked or have a brake applied thereto, and a lock or brake releasing position, wherein the locking of or the brakes applied to the tape reels are released; and a position regulating portion provided in the case main body for regulating the position of the reel brake at a position where the reel brake locks the tape reels, wherein a gate portion for the reel brake is provided at a front of a main body of the reel brake, and wherein a run off portion is formed such that the gate portion formed at the front of the main body of the reel brake does not abut with the position regulating portion when the front of the main body of the reel brake is brought into abutment with the position regulating portion. Preferably, a runoff portion is formed in the position regulating portion for avoiding an abutment between the reel brake and the gate portion.
In the second aspect of the present invention, when the front of the main body of the reel brake abuts with the position regulating portion, the gate portion at the front of the main body of the reel brake does not abut with the position regulating portion. Therefore, even if there remains a projection (the remains of the gate) at the gate portion, the reel brake is allowed to slide to a position where the reel brake can be brought into secure abutment with the tape reels.
Moreover, the run off portion formed in the position regulating portion side functions to avoid a risk of an abutment between the gate portion of the reel brake and the position regulating portion. Therefore, there is no need to form a thickness saving portion or the like on the reel brake side.
According to the third aspect of the present invention, a tape cassette comprises a pair of tape reels around which a tape is wound rotatably received in a case, the tape being disposed so as to extend from one of the tape reels through a front of the case to the other tape reel to be wound up therearound, and a reel brake member having brake pawls for suppressing the rotation of the tape reels and provided so as to freely slide for engagement with and disengagement from teeth of the tape reels for braking operation and brake releasing operation, respectively, the reel brake member being biased by a spring toward a tape reels side, wherein a main body of the reel brake member comprises an opening hole portion for insertion of a brake release member provided on a device side, and wherein a guide recessed portion is formed at a center of an abutment side wall portion of the brake release member within the opening hole portion for guiding the brake release member.
In addition, the guide recessed portion is formed in a vertical direction in the abutment the wall portion of the brake release member at a central portion of the opening hole portion, and an internal surface of the guide recessed portion is formed into a curved surface.
Furthermore, the abutment side wall portion of the brake release member is formed into an inclined surface on a lower the thereof, while the abutment side wall portion is, formed into a vertical surface on an upper side thereof, and both sides of the guide recessed portion into which the brake release member is fittingly inserted are formed into flat surface portions.
According to a mode of operation of the present invention, in a case, a reel brake member biased by a resilient force so as to engage tape reels is restricted with respect to a movable range thereof by a regulating mechanism for preventing the movement of the reel brake member to such an extent that brake pawls of the reel brake member are released from an engagement with tape reels. In other words, the reel brake member comprises an opening hole portion for insertion of a brake release member provided on a device side, and a guide recessed portion is formed at a center of an abutment side wall portion of the brake release member within the opening hole portion for guiding the brake release member. With this construction, even if there is a change in the type of machine on the device side involving various types of brake release members, a central portion of the reel brake member can be pressed for operation at all times, whereby a smooth brake release operation can be effected, and the brake function can be maintained in a normal fashion, thus there being caused no problem in handling the same. In addition, in a brake release means for use with a recording and reproducing device, the main body of the reel brake member facing the opening of the case abuts with the brake release member to thereby cause the reel brake member to slid and move so that the brake pawls can securely be disengaged from the teeth of the brake potion for safety running of a tape inside.
According to the fourth aspect of the present invention, a tape cassette comprises a pair of tape reels around which a tape is wound rotatably received in a case, the tape being disposed so as to extend from one of the tape reels through a front of the case to the other tape reel to be wound up therearound, and a reel brake member having brake pawls for suppressing the rotation of the tape reels and provided so as to freely slide for engagement with and disengagement from teeth of the tape reels for braking operation and brake releasing operation, respectively, the reel brake member being biased by a spring toward a tape reels side, wherein a main body of the reel brake member comprises arms provided on sides thereof via hinge portions, each of the arms having a brake pawl provided on a distal end thereof, an opening hole portion formed therein for insertion of a brake release operating member provided on a device side, upper and lower surface portions adapted to abut with and slide over internal surfaces of upper and lower cases, recessed portions provided on sides of a front side of the upper surface portion at positions corresponding to outer circumferential edges of the tape reels, and a butt recessed portion formed on a front side of the lower surface portion in such a manner as to correspond to holding ribs provided on a front side of a reel brake sliding area of the lower case along a tape reel receiving area.
In addition, in the present invention, a regulating wall portion for regulating the sliding of the arm of the reel brake member is a guide rib, and the guide rib comprises a linear guide rib oriented toward a back side of the case and a curved guide rib provided on a front side of the case so as to extend outwardly. The linear guide rib and the curved guide rib are provided on internal surfaces of the upper and lower cases in such a manner as to protrude therefrom. In addition, the curved guide rib is provided so as to extend at a height which is taller than the linear guide rib. When the reel brake member is in a brake state, the transverse position of the reel brake member is regulated only on the rear side thereof, and the front side of the reel brake member is allowed to transversely rotate to some extent.
Furthermore, a projection is provided on the arm of the reel brake member in such a manner as to protrude therefrom for abutment with the guide rib, and guide wall portions which the arms of the reel brake member slide along and abut with are provided continuously with outer circumferential ribs provided along the tape reels receiving area. Thus, with the above construction, a regulating mechanism for regulating the movement of the reel brake member in a brake releasing direction functions as the regulating wall portion and prevents the arms of the reel brake member from deflecting inwardly of the brake when the tape cassette is not in use or while the brake releasing operation is being carried out, whereby the brake pawls are constructed not to disengage from the reel areas. Moreover, the reel brake member closes inwardly the arms of the reel brake member in the vicinity of the brake releasing position so that the brake pawls disengage from the reel areas.
In a case, a reel brake member biased by a resilient force so as to engage tape reels is restricted with respect to a movable range thereof by a regulating mechanism for preventing the movement of the reel brake member to such an extent that brake pawls of the reel brake member are released from an engagement with tape reels. In other words, the reel brake member comprises arms provided on both sides of a main body thereof via hinge portions, respectively, the respective arms having the brake pawls at distal ends thereof, a projection provided between the arm and the brake pawl, upper and lower surface portions adapted to slide over internal surfaces of upper and lower cases of the tape cassette, recessed portions formed on the upper surface portion on both sides of the front side at positions corresponding to outer circumferential edges of the tape reels, and a butt recessed portion formed on a front side of the lower surface portion in such a manner as to correspond to holding ribs provided on a front side of a reel brake sliding area of the lower case along a tape reel receiving area. In addition, a regulating wall portion for regulating the sliding of the arm of the reel brake member is a guide rib, and the guide rib comprises a linear guide rib oriented toward a back side of the case and a curved guide rib provided on a front side of the case so as to extend outwardly. Thus, the movable range of the arms of the reel brake member are restricted and regulated, whereby even if an external strong force due to a strong impact such as a drop impact is exerted thereon, the reel brake is prevented from being disengaged. In addition, even if the tape is moved in the tape cassette, since there is no chance for the flange to abut with the reel brake member main body (there is no chance for the brake to be moved by the flange), it is possible to eliminate unnecessary movements of the reel brake member, whereby a secure brake can be provided. In addition, since the reel brake member can transversely rotate (oscillation) at the brake position in conjunction with the respective movements of the respective reels, the reel brake member can follow every movement of the tape, whereby a highly reliable brake condition can be maintained. Moreover, the production of a looseness of the belt is thus prevented from occurring, and there is no risk of problems being generated when the tape cassette is mounted in the recording and reproducing device for use. In addition, the brake release means of the recording and reproducing device abuts with the brake release operating portion of the reel brake member to thereby slidingly move the reel brake member in the sliding operation so that the brake pawls are disengaged from the teeth of the tape reels for safely running of the tape.